The applicant's long-term career goal is to develop scientifically-based therapies to advance the physical rehabilitation and recovery of function in persons after spinal cord injury (SCI). The applicant's current goal is to build on her clinical expertise in SCI physical rehabilitation, apply her doctoral training in motor control, and merge advanced knowledge and research skills to develop as an independent and competitive investigator bridging basic and clinical research in SCI rehabilitation. A five-year research and training plan developed with the primary mentor, F. Thompson, PhD of the University of Florida Brain Institute (UFBI) will meet this goal. This plan capitalizes on current collaborations, mentorship, and research expertise of SCI researchers at the UFBI. The aims of this award are to: 1) enrich the candidate's research and experimental design skills; 2) advance current knowledge of spinal cord neurophysiology and activity-dependent plasticity; 3) develop the techniques to assess spinal cord neurophysiological function; and 4) enhance research support skills including scientific writing and grantsmanship. New approaches to facilitate locomotor recovery in individuals after SCI have recently been explored that optimize activity- dependent plasticity using sensory information related to locomotion to improve walking. Locomotor training velocity may be a critical, activity-dependent parameter affording appropriate phasic input to the neural system. In the proposed research, the relationship between neurophysiological mechanisms that sub-serve locomotion and walking velocity overground and on a treadmill will be compared in control subjects and subjects with incomplete SCI. For subjects with incomplete SCI, the effects of training velocity and a long-term locomotor training program on spinal cord reflex modulation function and overground walking velocity will then be assessed. The goal of this research is to assess if long-term locomotor training at a specific velocity in individuals with incomplete SCI will better facilitate neuroplasticity measured by improvements of spinal cord reflex function and increases in walking velocity.